Mobile excavator with adjustable boom

ABSTRACT

A mobile excavator having a self-powered frame structure supporting a platform for rotation about a vertical axis with a boom pivoted adjacent one edge on the platform and a material handling device pivoted on the free end of the boom. The boom and material handling device are respectively pivoted by fluid motor means and the boom is formed in two sections. The adjacent ends of the two sections are pivotally interconnected and releasable fastening means are used for maintaining the boom sections in any one of a plurality of pivoted, angularly related adjusted positions to thereby vary the range of operation of the material handling device. The material handling device is pivoted on the boom with two fluid motors so that the entire machine is very compact and still is capable of digging over a wide range.

United States Patent Symmank 51 Aug. 1,1972

[54] MOBILE EXCAVATOR WITH ADJUSTABLE BOOM [72] Inventor: William D. Symmank, Schofield,

Wis.

[73] Assignee: J. I. Case Company [22] Filed: July 22, 1970 [21] Appl. No.: 57,035

[52] US. Cl. ..214/138 R [51] Int. Cl. ..E02f 3/00 [58] Field of Search ..214/138, 138 B, 138 C, 145

[56] References Cited UNITED STATES PATENTS 3,465,904 9/1969 Pensa .214/ 138 2,961,106 11/1960 Davis ..214/138 3,291,328 12/1966 Brocklebank ..214/ 138 Primary Examiner-Gerald M. Forlenza Assistant Examiner-Jerold M. Forsberg Attorney-Dressler, Goldsmith, Clement & Gordon [57] ABSTRACT A mobile excavator having a self-powered frame structure supporting a platform for rotation about a vertical axis with a boom pivoted adjacent one edge on the platform and a material handling device pivoted on the free end of the boom. The boom and material handling device are respectively pivoted by fluid motor means and the boom is formed in two sections. The adjacent ends of the two sections are pivotally interconnected and releasable fastening means are used for maintaining the boom sections in any one of a plurality of pivoted, angularly related adjusted positions to thereby vary the range of operation of the material handling device. The material handling device is pivoted on the boom with two fluid motors so that the entire machine is very compact and still is capable of digging over a wide range.

3 Claims, 3 Drawing Figures BACKGROUND OF THE INVENTION The present invention relates generally to material handling devices and more particularly to an improved boom structure for mobile excavators.

One type of known material handling device, which has been in existence for some time, includes a boom carried by a support for pivotal movement in a substantially vertical plane about a horizontal axis. The boom is generally pivoted on the support by a fluid power means while the support is rotatable about a vertical axis on self-powered frame.

The free end of the boom pivotally supports a material handling unit, such as a dipper stick having a bucket pivoted thereon. The dipper stick is again pivoted relative to the free' end of the boom through additional fluid power means while the bucket is pivoted on the dipper stick through a further fluid power means. Devices of this general character are shown in Przybylski U.S. Pat. No. 3,392,855 and Davis, U.S. Pat. No. 2,961 ,106.

While devices of this type have found a remarkable degree of commercial success, the construction and arrangement of the various parts in commercial machines heretofore known, has placed limitations on the overall operation of the machine. In machines of the above mentioned type, in many instances it becomes desirable to increase the operational depth of a device in a digging operation while in other instances it may be desirable to sacrifice working depth of the material handling device in order to lift the material handling means a considerable distance above the ground level. While devices have been proposed for forming the boom in two sections and adjusting the sections to vary the effective working depth and elevational height of the dipper forming part of the material handling means, such devices have been extremely complicated and require additional parts which considerably increase the cost of the overall unit. One such example of a complicated mechanism for performing the above functions is disclosed in Pensa, U.S. Pat. No. 3,465,904.

While the material handling mechanism disclosedin Pensa is capable of adjustment, devices of this general character have not been readily accepted commercially because of other serious drawbacks. In addition to the extremely complicated mechanism for adjusting the two sections of the boom, the Pensa device further has drawbacks relating to the operational capabilities of the material handling unit. For example, the location of the power means for the boom, as well as the location of the pivot axis of the boom on the platform or turntable, severely restricts the operating depth of the boom. The depth limitations are further restricted when designing a self-propelled vehicle of the wheeled type since the size of the wheel and the associated tires, necessary for supporting the extreme amount of weight, place the turntable or pivoted platform a considerable distance above the ground level. In addition, when operating the excavator along a line extending over either of the wheels, the fenders which normally extend above the wheels, further restrict the working depth in this area.

While the desired depth may be achieved by extending the length of the boom, such an arrangement is undesirable since it requires a considerable additional amount of clearance above the vehicle when the boom is required to be elevated for high dumping clearance. Furthermore, the mechanism would still have depth restrictions when operating over the areas of the rear wheels.

Thus, there remains a need for a structurally simple and compact excavating machine which is capable of digging in close proximity to the machine frame as well as a considerable distance from the machine frame.

SUMMARY OF THE INVENTION The present invention contemplates a neat and compact mobile excavator which is capable of operating in an area' with a minimum overhead clearance and will allow the apparatus to operate at a considerable depth. Stated another way, the present invention contemplates the arrangement and interconnection of the plurality of parts normally forming a part of commercially known excavators in such a manner that an extremely compact unit is capable of digging or excavating in a range which is a considerable distance from the transport frame to an area adjacent to and directly underneath the transport frame. The arrangement of parts further accommodates increasing the effective maximum dumping clearance by a simple adjustment of two relatively movable parts.

structurally, the present invention contemplates a mobile excavator having a self-powered or selfpropelled frame supported on spaced wheels and a turntable or platform revolvable about a vertical axis above the frame. A boom is pivoted adjacent a lower and outermost end portion of the platform or turntable and is pivoted between raised and lowered positions by a fluid power means located above the pivot axis for the boom. In addition, the boom is formed in two sections pivotally interconnected at adjacent ends and pivotable to a plurality of angularly related positions, with releasable pin means or. fastening means being provided for securing the sections in any one of a plurality of adjusted positions.

According to another aspect of the present invention, the dipper stick normally connected to the free end of the boom has a relatively small overlapping portion extending above the boom and is pivoted by a pair of spaced fluid power means so as to further reduce the overall effective length and height of the unit, particularly when the unit is in a transport position.

The particular arrangement of the various components forming the excavator of the present invention is capable of performing operations heretofore requiring parts of considerable greater length thereby increasing bulkiness of the machine as well as the overall size of the unit in the transport position.

DETAILED DESCRIPTION OF THE SEVERAL VIEWS OF DRAWINGS DETAILED DESCRIPTION While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one specific embodiment, with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiment illustrated.

FIG. 1 of the drawings discloses a mobile excavator generally designated by the reference numeral 10, constructed in accordance with the present invention and shown in the transport position. The excavator includes a self-powered framed structure consisting of a frame 12 supported by a plurality of wheels 14 and defining a circular support 16 adjacent the upper end thereof. A platform or turntable 18 is supported for rotation about a vertical axis on the circular table 16 and is rotatable through a complete circle of revolution relative to the frame structure 12.

The platform 18 has an operators station or cab 20 which is laterally offset from the pivot axis of the platform, and a boom, generally designated by the reference numeral 22, pivoted about a horizontal pivot axis, defined by a pin 24. The boom is pivoted about the horizontal pivot pin 24 through a fluid ram 26 having one end pivoted on the platform 18 above the pivot axis 24 and the opposite end pivotally connected to the boom structure at a point spaced from the pivot axis 24. The boom structure has material handling means 30 pivotally connected to the free end thereof and movable to a plurality of positions by an additional fluid motor means or ram 32, both of which will be described in more detail hereinafter.

According to one aspect of the present invention, the boom 22 is constructed in a manner and cooperates with the platform to accommodate operation or digging to a substantial depth in close proximity to the frame structure of the excavator. As more clearly shown in FIG. 2, the pivotal connection 24 between the platform 18 and the boom structure 22 is located adjacent the lower surface of the platform and along an extreme end of the platform to be in close proximity to the adjacent edge of the frame structure 12. In addition, the fluid ram 26, consisting of a cylinder 34 and a piston rod 36, is disposed above the horizontal pivot axis 24 and overlies the adjacent end of the boom 22.

This arrangement will at all times have the cylinder protected by the large rigid boom 22 and will allow the operator to dig to substantially the same depth along substantially the entire circumferential area surrounding the mobile frame. This is of considerable advantage over excavators of the type wherein the fluid ram is located below the boom structure which required that the operator be at all times cognizant of the location of the frame structure and fenders relative to the fluid ram to prevent the fluid ram from being forced into engagement with the frame structure and possibly damaging the entire unit.

Additionally, by locating the pivot point 24 as low as possible on the platform, and adjacent a remote end of the platform, the outer range limits of operation can be considerably increased without the necessity of increasing the operative length of the boom structure and/or the material handling means or structure 30.

The pivot axis 24 is laterally offset a substantial distance from the vertical pivot axis of the platform. Thus, the overall length of the boom structure 22 may be reduced by the lateral offset distance without sacrificing distance on maximum reach of the excavating unit.

This arrangement also makes the overall unit more compact in the transport position shown in FIG. 1, since the overall length of the unit is, to a large extent, determined by the length of the boom 22.

According to another aspect of the present invention, the maximum digging depth and the maximum dumping clearance can readily be adjusted so as to in crease the versatility of the machine without excessively increasing the cost thereof. This is accomplished by forming the boom 22 of two sections 40 and 42 which are pivotally interconnected at adjacent ends by first pin means 44 that will accommodate pivotal movement of the second or outer section relative to the first or inner section to a plurality of pivoted positions.

The boom structure 22 further includes second pin means or releasable fastening means for securing the outer section in any one of a plurality of adjusted angularly related positions relative to the first or inner section. In the illustrative embodiment, the releasable fastening means 48 is adapted to extend through any one of a plurality of openings 46, which are circumferentially spaced about a common radius relative to the pin 44, and through a single opening not shown, in the second section 42, which is adapted to be aligned with any one of the plurality of openings 46. Thus, the pins 44 and 48 as well as the openings in the respective sections 40 and 42, define adjustment means for varying the angular relation of the elongated sections of the boom structure 22.

FIG. 2 shows the boom sections 40 and 42 adjusted to a lowermost or angularly related position for operation at maximum depth and minimum dumping clearance, respectively shown by the solid line and dotted line positions of the material handling unit, and it will be noted that in this position, the location of the interconnection between the boom structure 22 and the platform 18 as well as the location of the location of the fluid ram 26 will allow the performance of a digging operation in close proximity to the frame structure without the need of the operator having to keep a lookout to prevent the fluid ram striking the frame and causing damage to the structure. It will also be noted that the pivotal connection 44 for the two sections is located beyond the frame 12 to allow the longitudinal axes of the respective sections to be located substantially perpendicular to each for maximum depth operation in close proximity to the frame even over the area of the wheels 14.

FIG. 3 shows the boom sections 40 and 42 interconnected in an adjusted position where the elongated axes of the respective sections are in substantial alignment with each other so that the unit can be raised to a maximum dumping height and the digging operation can be initiated at a point a considerable distance away from the supporting structure for the unit. It should be noted at this point, that by arranging the fluid ram 26 so as to be extended during the lowering operation, the larger surface area of the piston(not shown)in the rams may be utilized during the initial portion of the digging operation. Also, the location of the ram 26 above the boom 22 places the ram in tension during the lifting operation as opposed to being in compression when the boom ram is below the boom. In the latter case, the extended boom ram forms a column which will have the ram elements subjected to bending moments in the fully extended position.

According to a further aspect of the present invention, the material handling means 30 and the fluid motor means 32 are constructed in such a-manner and cooperate with each other to minimize the projection of either of the elements above the pivot axis on the free end of the boom structure 22 during operation thereof. Heretofore, it has been common to pivot the material handling means or dipper stick assembly 30 by a single fluid motor means or ram 32. In order to produce the necessary forces required for performing the digging operation, this arrangement required an extremely large and long fluid ram 32 cooperating with the boom structure and the adjacent end of the dipper stick assembly 30. In addition, the size of the fluid ram 32 and the length thereof required a long portion of the dipper stick assembly to extend beyond the pivot axis on the boom towards the fluid ram 32. This extension or leverage, which extended beyond the pivot axis of the boom structure, greatly increased the amount of clearance required for operation above the ground level or when moving the dipper stick assembly to the dump position. Also, the length of the leverage contributed significantly to the overall height of the machine in the transport position.

According to another aspect of the present invention, these problems are substantially eliminated by utilizing a pair of fluid rams 50 and 52, located in sideby-side relation, which define the fluid power means 32. The fluid rams each include a piston rod 56 extensible and retractable relative to a cylinder 54 with the cylinders connected at a common location on the second section 42 and the piston rods connected to the adjacent end of the dipper stick so that simultaneous extension and retraction of said fluid rams will pivot the dipper stick on the boom. Thus, the duel fluid rams 50 and 52 can be considerably shorter and smaller in diameter than the single unit thereby allowing the overall length of the leverage to be substantially shorter than was heretofore common. The shorter leverage or overlapping portion of the dipper assembly and the adjacent boom structure may be incorporated without sacrificing maneuverability of the dipper stick assembly.

As is shown in FIGS. 2 and 3, the dipper assembly 30 includes a dipper stick 60 pivotally connected intermediate its ends, at 62, to the free end of the boom structure 22. The remote or opposite end of the dipper 60 has a bucket 64 pivotally secured by pin 65 and is movable to any one of a plurality of positions by mechanism including fluid motor means 66. The interconnection between the piston rod of the fluid motor means 66 and the bucket 64 includes a compound linkage 68 having the adjacent interconnected ends connected to the piston rod of the motor and the respective outer ends, respectively pivotally connected to the dipper stick 60 and the bucket 64.

According to a further aspect of the present invention, greater maneuverability of the bucket on the dipper stick is accomplished in a simple and effective manner. Heretofore, in order to increase the dumping angle of the bucket on the dipper stick, it was necessary to disconnect the bucket from the dipper stick by removing pivot pin 65 and reconnect the bucket to the dipper stick at a different location. However, according to he present invention, the variations in dumping angle are accomplished without removing the bucket from the dipper stick. The larger amount of pivotal movement of the bucket 64 relative to the dipper stick 60 is achieved by changing the connection of the linkage on the bucket. In the illustrated embodiment, the link 68a of the compound linkage 68 may be connected to the bucket through any one of a plurality of spaced openings 70 to thereby increase or decrease the amount of pivotal movement of the bucket relative to the dipper stick as the fluid ram 66 is moved between retracted and extended positions. This arrangement considerably simplifies the work required to change the amount of pivotal movement of the bucket 60 with the openings 70 and the associated pin (not shown) defining means for changing the pivotal connection of the linkage on the bucket.

FIG. 1 of the drawings discloses the dipper stick in a transport position for transporting a large distance. This is accomplished by removing the fluid ram assembly 66 and the compound linkage 68 and connecting the bucket 64 to the pivot point for the fluid ram on the dipper stick. This will allow considerable compaction of the elongated length of the dipper stick assembly 30 for transportation.

Thus, it will be appreciated that the present invention provides an extremely simple structural arrangement of parts forming the necessary elements of a compound excavating unit with the parts being operatively interconnected and movable to allow the utilization of extremely simple parts and which can readily be adjusted to suit several different purposes. Furthermore,

the entire unit can be readily arranged for transportation between operating sites.

WHAT IS CLAIMED IS:

1. A mobile excavator comprising: a self-powered frame structure; a platform revolvable about a vertical axis on said frame structure; a boom having first and second sections; pivot means adjacent the lower end of said platform at one extreme end thereof and defining a horizontal axis; means mounting said first boom section for pivotal movement about said axis from an upwardly inclined transport position to a generally horizontally disposed working position; first fluid motor means connected between said first boom section and said platform for pivoting said boom about said horizontal axis, said first fluid motor means being positioned above said first boom section whereby said first boom section can be pivoted from said transport position to said working position without interference with said frame structure; material handling means including a dipper stick pivoted intermediate its ends on said second boom section, means for pivoting said dipper stick relative to said second boom section, a bucket pivoted on a free end of said dipper stick, and means for pivoting said bucket and including a bucket fluid motor means connected between said dipper stick and said bucket; first pin means connecting said second boom section to said first boom section and cooperating with said boom sections to define an adjustment pivot means permitting said second boom section to be selectively pivoted relative to said first boom section between a plurality of angularly spaced positions; means for retaining said second boom section in the selected position including an opening in said second boom section, a plurality of spaced openings in said first boom section defining said positions, and second pin means insertable in the opening in said second boom section and in the selected opening in said first boom section, said openings in said first boom sections being disposed along an arc having a common radius about said first pin means, one of said openings being located so as to position said second boom section generally horizontally in the transport position (FIG. 1) and in a maximum height working position (FIG. 3) wherein said bucket is movable along an are that is positioned vertically above the first mentioned pivot means, another of said openings being located so as to position said second boom section in a vertically downwardly extending maximum depth working position (FIG. 2) wherein said bucket is movable along an arc vertically below said frame structure.

2. A mobile excavator as defined in claim 1, in which said means for pivoting said dipper stick includes first and second fluid rams cooperating with said dipper stick and said second section.

3. A mobile excavator as defined in claim 1, in which said means for pivoting said bucket further includes compound linkage means pivoted on said dipper stick and said bucket, and means for changing the pivotal connection of said linkage means on said bucket whereby to change the amount of pivot of said bucket on said dipper stick in response to extension and retraction of said bucket fluid ram. 

1. A mobile excavator comprising: a self-powered frame structure; a platform revolvable about a vertical axis on said frame structure; a boom having first and second sections; pivot means adjacent the lOwer end of said platform at one extreme end thereof and defining a horizontal axis; means mounting said first boom section for pivotal movement about said axis from an upwardly inclined transport position to a generally horizontally disposed working position; first fluid motor means connected between said first boom section and said platform for pivoting said boom about said horizontal axis, said first fluid motor means being positioned above said first boom section whereby said first boom section can be pivoted from said transport position to said working position without interference with said frame structure; material handling means including a dipper stick pivoted intermediate its ends on said second boom section, means for pivoting said dipper stick relative to said second boom section, a bucket pivoted on a free end of said dipper stick, and means for pivoting said bucket and including a bucket fluid motor means connected between said dipper stick and said bucket; first pin means connecting said second boom section to said first boom section and cooperating with said boom sections to define an adjustment pivot means permitting said second boom section to be selectively pivoted relative to said first boom section between a plurality of angularly spaced positions; means for retaining said second boom section in the selected position including an opening in said second boom section, a plurality of spaced openings in said first boom section defining said positions, and second pin means insertable in the opening in said second boom section and in the selected opening in said first boom section, said openings in said first boom sections being disposed along an arc having a common radius about said first pin means, one of said openings being located so as to position said second boom section generally horizontally in the transport position (FIG. 1) and in a maximum height working position (FIG. 3) wherein said bucket is movable along an arc that is positioned vertically above the first mentioned pivot means, another of said openings being located so as to position said second boom section in a vertically downwardly extending maximum depth working position (FIG. 2) wherein said bucket is movable along an arc vertically below said frame structure.
 2. A mobile excavator as defined in claim 1, in which said means for pivoting said dipper stick includes first and second fluid rams cooperating with said dipper stick and said second section.
 3. A mobile excavator as defined in claim 1, in which said means for pivoting said bucket further includes compound linkage means pivoted on said dipper stick and said bucket, and means for changing the pivotal connection of said linkage means on said bucket whereby to change the amount of pivot of said bucket on said dipper stick in response to extension and retraction of said bucket fluid ram. 